Cause and effect: The full story behind Just Cause 2’s multiplayer mod

Just Cause 2 didn't ship with a multiplayer mode at launch. But that didn't stop six members of the community making one.

Just Cause 2 didn't have a multiplayer feature at launch. Could you imagine four models of salty protagonist Rico Rodriguez swinging from mountain to mountain, spraying bullets at vehicles hundreds of feet away?

Six members of the game's dedicated community could. Skilled modders "jaxm" and "Trix", had just abandoned supporting their work adding multiplayer modes to Grand Theft Autos Vice City and San Andreas (dubbed Multi Theft Auto) when they spotted the Just Cause 2 demo. It became the perfect modern piece of software for the duo to sink their creative teeth into.

"In early March 2010, I came across Just Cause 2 and was blown away immediately. The sheer scale of the game, even from the demo, was incredible. The graphics were fantastic and the performance of the game made it evident that it was really well optimized," jaxm said in an interview with VideoGamer. "At this point, I practically started begging Trix to check out the Just Cause 2 demo.

"After he downloaded it, Trix felt the same way I did about the game and from this point on, we started throwing around ideas for what could be done with the game. Thus, JC2-MP was born."

The small team wasn't commissioned by the game's developer to work on this multiplayer feature, but Trix didn't need the guarantee of a fat paycheck to devote endless hours to the project: a steady day job as a malware analyst gave him both the financial means and technical knowhow to engage in a procedural undertaking of this magnitude. Breathing new life into existing properties was a personally fulfilling hobby for someone with Trix's degree of engineering curiosity.

"Once the full version of the game was released, I immediately began reverse engineering it, looking for regions of code and memory that I could make use of to influence the game," Trix admitted. "The earliest video we released of jaxm and myself driving through the snow was the result of around eight to 12 hours of programming and reverse engineering. It was at that point, driving around with another player, that I truly realized my love for the game."

The enthusiasm was there, but it takes more than two community members to build something of this scale. Fortunately for Trix and jaxm, the modding world isn't lacking in talent, so it wasn't long before a group of eager creators jumped on board. "Woet", a former member of the San Andreas multiplayer beta team, quickly saw the promise in the modding duo's early work - sensing the future potential of the bombastic addition.

"I met Trix and jaxm while being a member of the SA-MP beta squad and left the team around the same time as them. We didn't have much contact back then, but somewhere in 2010 they gave me a call and showed me a private YouTube video of basic vehicle sync in Just Cause 2," Woet said. "I had never heard about the game before this but it looked amazing, and I instantly bought it.

"They asked me to create a website for the mod, and I asked an amazing designer I've known for a long time - Tomislav Pocedulic - to design it. We had a small forum and released news on a regular basis, but after a while, Trix lost interest after hitting big obstacles during development. Since that day, I kept asking about the progress on a regular basis, and after about two years, Trix randomly gave me a Dropbox link. He told me they'd been working on it again and had overcome the obstacles that stopped them earlier. That's when the project gained a lot of momentum, getting us to this point."

Soon, this ragtag group of loosely connected modders assigned each other official titles and roles. Trix became the lead programmer, with jaxm heading gameplay design. Woet assumed the role of the team's web developer, while fellow Grand Theft Auto beta tester "NVX" led server and client security. Philpax, an active member of the Gary's Mod community, took charge of the game's UI, API, and the majority of the reverse engineering. Lastly, avid Just Cause fan dreadmullet wrote the game's scripting. He, like most of his colleagues, was taken aback by what could be done within the game's code.

"I wasn't part of the original team, but I still remember the 2010 teaser videos," dreadmullet reminisced. "I was completely awestruck at the idea of multiplayer in the world of Panau. Just Cause 2 most definitely has the best world of any game, and the amount of potential for multiplayer is massive.

"When there were no updates for almost two years, I very reluctantly removed the JC2-MP Twitter to save space on my RSS feed. About a month later, I chanced upon a Retweet for the first public test. I dropped everything I was doing and joined. Despite the abysmal bugs and lack of sync, it was incredible. After playing single-player for a long time, just seeing other people drive and fly around was amazing."

What started as two friends with sharpened modding skills and a clever idea grew into a miniature development team composed of six acquaintances only aware of each other's existence through the modding grapevine. However, it was the pitch for the multiplayer mode that acted as an unbreakable thread keeping the virtually connected bunch tied together.

"I met my fellow developers upon joining the community; while I'd love to say that I'd known them before, the truth is I didn't have the foggiest clue of who they were before JC2-MP," Philpax admitted. "I'm happy to say that I'm good friends with all of them now, and that I'm much enriched for it."

Today, thousands of unique participants can enter a single multiplayer match with ease. However, the original goal wasn't nearly so ambitious. Everything started with the promise of four to eight players exploring the colossal environments, but a sleepless night of code experimentation opened Trix's eyes to the level of lunacy that could be unleashed upon the game's open world.

"In the early days, we hit a barrier where we couldn't spawn any more than eight vehicles at any given point," Trix explained. "Spawning any more than this required that you destroy one of the earlier vehicles to make room for it. This is largely one of the reasons for our disappearance after releasing our first video, since we simply couldn't break through that barrier.

"The initial idea was to have a small server setup where you and a few friends could drive your cars around and explore Panau together. However, the thought was short-lived, as a totally unplanned night of reverse engineering led us to implement on-foot player sync, suddenly opening up a whole world of new opportunities."

The mere thought of that much chaos in one place had the team salivating, even if the six modders had to rationalize that this wasn't a full-time, money-making operation. The ultimate goal was to create the best mod possible, but with other aspects of life tugging at each individual member's sleeve, compromises had to be made. This, of course, led to a bit of internal conflict.

"With a project as incredibly extensive as this, there were many scenarios where we ran into interpersonal conflict and a desire to overrule the other developers," Philpax confessed. "Ultimately, all of us had our own ideas as to where we wanted to go with JC2-MP; my role was to make it possible for others to achieve our own dreams and reach the heights that we personally could not achieve.

"I'll be honest and say that within the team, we could afford to communicate more. Several incidents and surprises arose due to our everlasting desire to make JC2-MP the best it could be while remaining realistic in the constraints that we faced - including time and real life factors. As a result of the fact we were working on it part-time, we had to continually re-evaluate what was possible with the limited time available to us.

"We all had our own personal challenges. I was, and still am, in full-time education, so we had to contend with this while simultaneously working on JC2-MP. With this, it's no surprise that we had to scale back what we wanted to do."

Trix expanded on Philpax's acknowledgment of the development realities, highlighting the recurring pressures of deadlines.

"Like any large-scale project, everyone wants new features. Some of these features are easy and take very little implementation time," he explained. "However, some of them require extensive reverse engineering which takes away from development. One of the problems we faced - and continue to face every day - is deadlines. Everyone wants to add new things, but at the same time, we wanted to get the release out the door.

"We found ourselves constantly overshooting because we couldn't stop adding to the project. Eventually as time went on, we collectively begun agreeing on things to put on the backburner in favor of getting the project released."

Heated arguments often stemmed from personal biases toward particular methods of development, while varying experience with different tools among the team made the project feel like, "a powder keg waiting to explode."

And yet, it was the unique internal design of the Just Cause 2 code that caused the most frequent frustrations.

"There's been the ongoing fight to balance code quality, implement new features, and fix bugs. As a result of how JC2-MP works, this is more difficult than for most other games and mods; we need to work around the original game's limitations and insert our own code, which can be a rather difficult proposition, especially without having access to the game's original code," Philpax said.

"Due to this constraint, we've inserted all kinds of ugly workarounds for issues that make working on the project more difficult; this ends up causing friction amongst us when we try and figure out what was going on six months later. Sometimes we get a little antsy when discussing code from the early days - a lot of assumptions were made back then that don't apply now.

"As time goes by, we're trying to clean up our code and make it easier to both implement new features and fix bugs, but this is obviously a slow, difficult process - especially when cleaning up and fixing issues takes longer than building on what's already there."

Even with extensive experience modding older games, the JC2-MP team couldn't predict every barrier standing in their way. Certain hurdles, such as the game's synchronization, had to be met head on before they could be cleared.

"One of the major issues we had to reevaluate was the improvement of sync. Due to our [at the time] lacking knowledge of network synchronization, optimization, and indeed the game itself, we had to make several compromises that have led to sacrifices in sync quality," Philpax clarified. "Now that JC2-MP has been officially released, we have free rein to investigate alternative solutions and vastly improve sync for the better."

All the hard work and late hours of development paid off when Avalanche - the studio responsible for Just Cause 2's existence - reached out to the JC2-MP team. Instead of slapping a cease and desist order in their collective inbox, Avalanche gave the fans its blessing. The mod got an official release on Steam in December 2013.

"Initially, we were just a few modders playing around with a game to see what we could do," Trix said. "The feedback we got from our YouTube video from both the community and Avalanche was totally unexpected. To have the game's developers commend your work is the highest honor any modder can receive, and we're truly humbled that they would give us their blessing and legal permission to continue building the project."

"Our unofficial modification was being endorsed, promoted and authorized by the very team that created the original product," Philpax added. "At that moment, I felt nothing but pride; we'd come far enough to be officially recognized. It's like the highest public stamp of approval we could've received - it simply is not something to be understated."

Seeing this level of support from the Just Cause 2 community, as well as the game's developer, has put even more pressure on the fanatical modding team. JC2-MP has more eyes on it than Trix or jaxm could have ever imagined, so while it remains a passion project, coming second to any individual member's full-time career, there's a sense of responsibility among the team to give the mod's hungry fans the best experience possible.

"If you let it, it can be as much work as a full-time job. Moderating the forums, IRC, wiki, writing documentation, making bug reports, and reviewing pull requests on our script repositories all take time away from actually adding to the mod itself," dreadmullet revealed. "And I'm trying to work on my racing game mode in the meantime.

"I feel a pressing obligation to improve the experience of thousands of people. Doing anything else with my time just seems selfish. Not that I'm really complaining - this is a dream project, and I'm extremely proud to be a part of it."

The project that each of the six members has dedicated years of work to is now available on Steam, which is a feeling that dreadmullet can only describe as "dreamlike." It might have arrived in an unorthodox manner, but Just Cause 2 finally has its multiplayer feature. Fortunately for its fans, there will be plenty of support for the flourishing mod in the future, as Philpax said that the team "doesn't see an end in sight."

The community will play a big role in keeping JC2-MP alive, but what will become of the six modders who've now been officially recognized by a major developer like Avalanche Studios? They all have their own independent goals, but Philpax hasn't ruled out breaking away from modding existing games to instead build something from scratch.

"I'd call myself a freelance video game programmer; while I haven't seen active employment as a video game developer outside of JC2-MP, I'd definitely want to develop my own game from scratch," he admitted."With the rest of the team? I'm not sure, to be honest we - all have differing visions on what we'd want from a game, and it's something I'd have to strongly consider before committing to.

"Being part of the modding community lets us extend games that already exist and bring new functionality to them, but it would be nice to be able to create our own games and see what we're really capable of. Maybe someday, eh?"

And who knows - there might just be the opportunity to work on the next Just Cause game with the actual creators of the series.

"Well, time will tell," Philpax continued. "I would love to work at Avalanche and push the frontiers of expansive open-world games; their games are simply fantastic, and I'd love to have an opportunity to directly work with them. I'll definitely consider applying once I'm able to seek full-time employment, even if it means a change of country.